Technical Field
The present disclosure relates to an imaging optical system and an image capturing apparatus. More particularly, the present disclosure relates to a compact imaging optical system and an image capturing apparatus which is applicable to electronic devices.
Description of Related Art
In recent years, with the popularity of mobile terminals having camera functionalities, the demand of miniaturized optical systems has been increasing. The sensor of a conventional optical system is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical systems featuring better image quality.
A conventional optical system employed in electronic devices mainly adopts four-element or five-element lens structures. As the popularities of smartphones and portable devices grow, highlighting the demand for compact electronic devices, the employed optical systems with large aperture and short total track length have become the new trend. However, the conventional optical systems cannot satisfy the requirements of both large aperture and short total track length simultaneously so it is difficult to apply them to compact electronic devices.
Other conventional optical systems with six-element lens structure are also developed. However, the conventional optical systems with features of large aperture and short total track length have excessive stray light so that the image quality cannot satisfy the requirements of customers.